The desire for motion even in still photos is somewhat demonstrated by the Ken Burns films ("The Civil War") in which his cameras move around still photographs, and give you a feel of motion, even though it's totally artificial.
If you think there is a sharp distinction between (good) film and art/still, get a movie you really like (Chinatown is a good one,) put it on an HD TV, then sit on your couch with a DSLR and take photos of it. You will astonish yourself with your new-found abilities.
I see many problems with the convergence, however. Many people don't want a picture to move -- they want to study it. Because of the way human vision works, it's surprisingly hard to study a moving picture, even with freeze-frame technology. In wildlife, for example, there is a distinct division between still artists and motion artists, although both kinds exist, because there's a distinct division between what is done with the art.
Also, as far as non-commercial photography goes, there's the problem of production costs, and I don't think that will change, except for jiggly, hand-held film shot by news people.
The biggest difference is that still is "a moment" and film is "a story" and what may be excellent in one medium is banal in another. This can be seen in television news, which has excellent film facility, as opposed to still photos. Often a still will be somewhat interesting, while the film turns out to be like one of those interminable C-Span shows of talking heads saying little; a film takes *time,* a still can be more of a "Blink" event, a gestalt thing, in which you soak up the essence in a second, then study for as long as you wish. Can't do that with film.
JC